High Voltage CMOS (HV-CMOS) Monolithic Active Pixel Sensor (MAPS) is currently one of the most promising candidates for the future upgrade of large detector systems due to many advantages such as being able to withstand higher luminosity, having better spatial and energy resolution, faster response rate and reducing the material budget and manufacturing complexity [1,2]. This paper presents a new Technology Computer Aided Design (TCAD) model of a completed pixel of a HV-CMOS MAPS including the detecting region and readout circuitry. Two types of readout electronics, a simple source follower amplifier and an integrated charge amplifier are implemented, studied and compared. The TCAD model is used to investigate and compare the electrical characteristics and performance of the sensor design with different dimensions, doping profiles, and bias conditions. The responses of the sensor due to incidence of a minimum ionization particle (MIP) at different energy levels are also considered. The result shows that at 120 V bias, the pixel is fully depleted and has a clear response for a MIP which generates approximately 7500 electron-hole pairs (ehps) when penetrating through 100 μm of Silicon. Both readout amplification designs show distinct signals. The integrated charge amplifier is more sensitive and suitable for detecting low signals. A noticeable output is produced for an incident particle that produces only 1000 ehps with the present design.
 I. Peric, "A novel monolithic pixel detector implemented in high-voltage CMOS technology," in 2007 IEEE Nuclear Science Symposium Conference Record, 2007, pp. 1033-1039.
 I. Perić, P. Fischer, C. Kreidl, H. H. Nguyen, H. Augustin, N. Berger, et al., "High-voltage pixel detectors in commercial CMOS technologies for ATLAS, CLIC and Mu3e experiments," Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, vol. 731, pp. 131-136, 2013